The present invention relates to the machine for applying bags or sacks to the discharge spouts of bag filling machines. More particularly, the invention relates to bag applying machines having a suction transfer device for advancing a bag towards the discharge spout of a filling machine and comprising opposed suction means for engaging opposite sides of the bag adjacent its mouth, and means for parting said opposed suction means so as to open the bag mouth for placing over the discharge spout. The bags or sacks handled by the machines may be made from paper, PVC or other plastics material.
United Kingdom Pat. No. 1439687 describes a bag applying machine comprising a suction pickup device which lifts a bag from a stack of flat bags and turns the bag from the horizontal position into a substantially vertical position, with its mouth disposed along one vertical side edge of the bag, and a suction transfer device which engages the bag held by the pick-up device, advances the bag from the pick-up device into an upright position adjacent the discharge spout of a bag filling machine, with the bag mouth uppermost, and opens the bag mouth for placing over the discharge spout. The pick-up device comprises a pair of pick-up arms rockable about a horizontal axis and carrying suction cups for gripping a bag. The stack of bags to be fed to the machine is disposed to one side of the machine and the pick-up arms rock downwardly to engage the suction cups with the top bag in the stack. Suction is thereupon applied to the cups so that they grip the bag and the arms are swung upwardly in a vertical arc to move the bag from the horizontal position, in which it is removed from the stack, into a substantially vertical position with its mouth disposed along one vertical side edge of the bag. In this position, the bag is gripped adjacent its mouth by the suction transfer device which comprises a pair of transfer arms pivoted on a horizontal axis ar right angles to the pivot axis of the pick-up device and having pairs of opposed suction cups for engaging opposite sides of the bag. Suction is applied to the transfer suction cups, which grip the bag, and is removed from the pick-up suction cups, which release the bag, and the transfer device then swings upwardly to remove the bag from the pick-up device and advance it to the discharge spout of the bag filling machine. At the same time, the transfer arms are moved apart so that the mouth of the bag is opened and placed over the discharge spout.
With a transfer device as described in the aforementioned specification, and other known types of transfer device, the open mouth of the bag is not formed to a satisfactory configuration for presentation to the discharge spout of the filling machine and, frequently, results in failure of the mouth to slip over the spout, or incorrect positioning on the spout, and improper operation of the filling process. Moreover, because the pick-up device comprises arms which swing in a vertical arc in order to turn the bag into a substantial vertical position for engagement by the transfer device, the pick-up device cannot commence its next cycle until the bag has been removed from its path of movement by the transfer device, thereby reducing the speed of operation of the machine. Moreover, only one pickup device can be provided for feeding the transfer device.